Because of how energy drain heavily impacts DPS the 8th weapon slot of a cruiser is typically a waste. And yes I do entirely dismiss the hull advantage because it only adds a bit more buffer which is not that important in the long run if the damage output is high enough to require a tank. On the other hand an escorts increased maneuverability and speed combined with the ability to mount dual cannons will by itself allow it to out damage the cruiser. That is before boffs are considered. The only aspect that is important is the higher shield multiplier that does grant the cruiser a slightly higher passive shield regeneration rate I will grant you that but it does not outweigh the bonus defense.
When tanking your maximum health is not the most important factor, infact it typically is not even a factor other than it needs to be high enough for you to live long enough for the heals to begin working their magic. What does matter is how much incoming damage you can mitigate with resistances or avoidance. When you have to tank 10k or 20k raw DPS having an extra 6k hull points is not going to mean squat. What will matter is if you can reduce that incoming damage by 3/4ths with your resistance and then by 1/4th with your bonus defense. Why is that so difficult to understand?
And for the idea that a science vessel or escort is wasting its potential by being setup as a tank just makes me laugh. If that is the case then any ship being setup as a tank is a waste, which is true. But even if it were not the cruiser would not be the best tank. The best self sustaining tank would be the Science Vessel and the best tank with a healer would be an escort. Yes it is true they would not be putting out their standard DPS or CCs with those setups but that would not be the role that they would be filling in the group. So if you think such a setup for those ships is silly now you know how I find your tank cruiser. Although I do personally enjoy silly setups and fly many myself so that is not meant as an insult you should fly what you enjoy I just want them to be more effective is all. I want the cruiser to have an advantage as the tank.
Just to illustrate what I mean by I enjoy silly setups I have flown a tank escort, Torpedo boats of all types, energy drain/support escorts, dps cruisers, support cruisers, every type of sci setup I could before they would end up getting nerfed, pretty much the only builds I haven't had much experience with are bomber/mine builds. It just saddens me that with the ship sale going I would love to buy the regent but cannot bring myself to do so as I know it will never be flown. I have a galor, I find it lacking and I know the regent is even weaker.